diff --git a/client/pyproject.toml b/client/pyproject.toml
index bcf32146..b7285543 100644
--- a/client/pyproject.toml
+++ b/client/pyproject.toml
@@ -34,7 +34,7 @@ certgrinder = "certgrinder.certgrinder:main"
 [project.optional-dependencies]
 dev = ["twine == 5.1.0", "pre-commit == 4.0.1", "setuptools-scm == 8.1.0", "build==1.2.2.post1"]
 test = ["pytest == 8.2.2", "pytest-cov==5.0.0", "tox == 4.20.0"]
-docs = ["Sphinx==7.3.7", "sphinx-rtd-theme==3.0.2", "sphinx-argparse==0.4.0"]
+docs = ["Sphinx==8.1.3", "sphinx-rtd-theme==3.0.2", "sphinx-argparse==0.4.0"]
 
 [project.urls]
 homepage = "https://github.com/tykling/certgrinder"